9.17 Subluxation of the Head of the Radius (Nursemaid's Elbow)

Presentation

A toddler has received a sudden jerk on his arm causing
enough pain that he holds it motionless. Circumstances
surrounding the injury may be obvious (such as a parent
pulling the child up out of a puddle); or obscure (the
babysitter who reports that the child "just fell down"). The
patient and family may not be accurate about localizing the
injury, and think that the child has injured his shoulder or
wrist. The patient is comfortable at rest, splinting his
arm with mild flexion at the elbow and pronation of the
forearm. There should be no deformity, crepitation,
swelling, or discoloration of the arm. There is also no
palpable tenderness except over the radiohumeral joint; the
child will start to cry with any movement of the elbow.

What to do:

Rule out any history of significant trauma, such as a fall
from a height.

Thoroughly examine the entire extremity, including the
shoulder girdle, hand and wrist,.

If there is any suspicion of a fracture, get an x ray.

When subluxation is suspected, place the patient in the
parent's lap and inform the mother or father that it appears
their child's elbow is slightly out of place and that you
are going to put it back in. Warn them that this is going to
hurt for a few moments.

Put your thumb over the head of the radius and press down
while you smoothly and fully extend the elbow, and at the
same time supinate the forearm. Complete the procedure by
fully flexing the elbow while your thumb remains pressing
against the radial head and the forearm remains supinated.
At some point you should feel a click beneath your thumb.
The patient will usually scream for a while at this point.
Leave for about ten minutes; then return and re-examine to
see that the child has fully recovered. Post-reduction
immobilization is usually unnecessary.

Reassure the parents, explain the mechanism involved in the
injury, and teach them how to prevent and treat recurrences.

Without full recovery, get x rays.

If x rays are negative, but the child still does not use
his arrn normally, place the arm in a sling and instruct the
family to seek orthopedic followup care if recovery doesn't
occur within 24 hours.

What not to do:

Do not attempt to reduce an elbow where the possibility of
fracture or dislocation exists.

Do not get unnecessary x rays when all the findings are
consistent with nursemaid's elbow. The x rays may appear
normal even when the radial head is indeed subluxed. The
dislocation is subtle, and requires measurement or
comparison to appreciate. (Draw a line down the axis of the
radius. It should bisect the capitellum of the lateral
humerus.) Associated fractures occur, yet are not common.

Do not confuse nursemaid's elbow with the more serious
brachial plexus injury, which occurs after much greater
stress and results in a flaccid paralysis of the arm.

Discussion

This injury is an anterior subluxation of the radial head
away from the capitellum through the annular ligament, and
occurs almost exclusively among children between 18 months
and 3 years of age. On occasion, if the subluxation has been
present for several hours, edema, pain, and natural
splinting will continue even after reduction, or may prevent
reduction.